Macrolide antibiotics and pulmonary inflammation

Erythromycin Formulations—A Journey to Advanced Drug Delivery

Erythromycin (ERY) is a macrolide compound with a broad antimicrobial spectrum which is currently being used to treat a large number of bacterial infections affecting the skin, respiratory tract, intestines, bones and other systems, proving great value from a clinical point of view. It became popular immediately after its discovery in 1952, due to its therapeutic effect against pathogens resistant to other drugs. Despite this major advantage, ERY exhibits several drawbacks, raising serious clinical challenges. Among them, the very low solubility in water and instability under acidic conditions cause a limited efficacy and bioavailability. Apart from this, higher doses promote drug resistance and undesirable effects. In order to overcome these disadvantages, during the past decades, a large variety of ERY formulations, including nanoparticles, have emerged. Despite the interest in ERY-(nano)formulations, a review on them is lacking. Therefore, this work was aimed at reviewing all efforts made to encapsulate ERY in formulations of various chemical compositions, sizes and morphologies. In addition, their preparation/synthesis, physico-chemical properties and performances were carefully analysed. Limitations of these studies, particularly the quantification of ERY, are discussed as well.

Comparison of prognostic factors between bacteraemic and non-bacteraemic critically ill immunocompetent patients in community-acquired severe pneumococcal pneumonia: a STREPTOGENE sub-study

Background

The presence of bacteraemia in pneumococcal pneumonia in critically ill patients does not appear to be a strong independent prognostic factor in the existing literature. However, there may be a specific pattern of factors associated with mortality for ICU patients with bacteraemic pneumococcal community-acquired pneumonia (CAP). We aimed to compare the factors associated with mortality, according to the presence of bacteraemia or not on admission, for patients hospitalised in intensive care for severe pneumococcal CAP.

Methods

This was a post hoc analysis of data from the prospective, observational, multicentre STREPTOGENE study in immunocompetent Caucasian adults admitted to intensive care in France between 2008 and 2012 for pneumococcal CAP. Patients were divided into two groups based on initial blood culture (positive vs. negative) for Streptococcus pneumoniae. The primary outcome was hospital mortality, which was compared between the two groups using odds ratios according to predefined variables to search for a prognostic interaction present in bacterial patients but not non-bacteraemic patients. Potential differences in the distribution of serotypes between the two groups were assessed. The prognostic consequences of the presence or not of initial bi-antibiotic therapy were assessed, specifically in bacteraemic patients.

Results

Among 614 included patients, 274 had a blood culture positive for S. pneumoniae at admission and 340 did not. The baseline difference between the groups was more frequent leukopaenia (26% vs. 14%, p = 0.0002) and less frequent pre-hospital antibiotic therapy (10% vs. 16.3%, p = 0.024) for the bacteraemic patients. Hospital mortality was not significantly different between the two groups (p = 0.11). We did not observe any prognostic factors specific to the bacteraemic patient population, as the statistical comparison of the odds ratios, as an indication of the association between the predefined prognostic parameters and mortality, showed them to be similar for the two groups. Bacteraemic patients more often had invasive serotypes but less often serotypes associated with high case fatality rates (p = 0.003). The antibiotic regimens were similar for the two groups. There was no difference in mortality for patients in either group given a beta-lactam alone vs. a beta-lactam combined with a macrolide or fluoroquinolone.

Conclusion

Bacteraemia had no influence on the mortality of immunocompetent Caucasian adults admitted to intensive care for severe pneumococcal CAP, regardless of the profile of the associated prognostic factors.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13613-021-00936-z.

Comparison of CRISPR and adenovirus-mediated Myd88 knockdown in RAW 264.7 cells and responses to lipopolysaccharide stimulation

Genomic manipulation offers the possibility for novel therapies in lieu of medical interventions in use today. The ability to genetically restore missing inflammatory genes will have a monumental impact on our current immunotherapy treatments. This study compared the efficacy of two different genetic manipulation techniques: clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR associated protein 9 (Cas9) transfection to adenoviral transduction to determine which method would provide the most transient and stable knockdown of myeloid differentiation primary response 88 (MyD88). MyD88 is a major regulator of nuclear factor kappa light chain enhancer of activated B cells (NFκB) pathway in Raw 264.7 macrophages. Following genetic manipulation, cells were treated for 24 h with Lipopolysaccharide (LPS) to stimulate the inflammatory pathway. Confirmation of knockdown was determined by western immunoblotting and quantification of band density. Both CRISPR/Cas9 and adenoviral transduction produced similar knockdown efficiency (~64% and 60%, respectively) in MyD88 protein 48 h post adenoviral transduction. NFκB phosphorylation was increased in CRISPR/Cas9-mediated MyD88 knockdown and control cells, but not in adenovirus-mediated MyD88 knockdown cells, following LPS administration. CRISPR/Cas9-mediated MyD88 knockdown macrophages treated with LPS for 24 h showed a 65% reduction in tumor necrosis factor alpha (TNFα) secretion, and a 67% reduction in interleukin-10 (IL-10) secretion when compared to LPS-stimulated control cells (P ≤ 0.01 for both). LPS did not stimulate TNFα or IL-10 secretion in adenovirus-mediated control or MyD88 knockdown cells. These data demonstrate that Raw 264.7 macrophages maintain responsiveness to inflammatory stimuli following CRISPR/Cas9-mediated reductions in MyD88, but not following adenovirus-mediated MyD88 knockdown.

Invasive Pneumococcal Disease in a Patient With COVID-19: A Case Report

The spread of the new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes coronavirus disease 2019 (COVID-19), has resulted in a global health pandemic and caused profound morbidity and mortality worldwide. The virus is known to cause severe hypoxemic respiratory failure and has been associated with extrapulmonary manifestations and end-organ dysfunction in the setting of extensive inflammatory response. Recently, the association between COVID-19 and pneumococcal pneumonia co-infection or superinfections has gained increasing interest. In this report, we present the case of a 58-year-old man with a past medical history significant for pulmonary tuberculosis, diagnosed over two decades ago, who presented with pleuritic chest pain, myalgia, intermittent fevers, chills, and productive cough and was found to have invasive pneumococcal disease and COVID-19. To our knowledge, this is the first reported case of invasive pneumococcal infection in a patient with COVID-19.

Sugaring-out extraction of erythromycin from fermentation broth

This study reports the sugaring-out extraction of erythromycin from fermentation broth using acetonitrile (ACN) as solvent and glucose as a mass separating agent. Different process parameters-glucose concentration, temperature, ACN/water ratio and pH-were optimized to achieve maximum extraction of erythromycin. 88% (w/w) of erythromycin was extracted from the model system with following optimized conditions: glucose 156.3 g/L; temperature 4 °C; ACN/water ratio 1 and pH 8.3. Further, the effect of typical fermentation media components (starch, soybean flour, CaCO₃, NaCl and (NH₄)₂SO₄) on sugaring out extraction of erythromycin was also investigated. Starch, soybean flour and CaCO₃ were observed to affect erythromycin extraction only at higher concentration. Removal of suspended solids from simulated as well as real broth prior to extraction enhanced the extraction efficiency (from 72% to 87%). Sugaring out extraction of erythromycin was found to be more effective than salting out extraction. Also, higher partition coefficient was achieved in the present work than other reported methods using carbohydrates as mass separating agent. Further, it was found that the antimicrobial activity of erythromycin was preserved during sugaring out extraction of erythromycin.

The Role of Specialized Pro-Resolving Mediators in Cystic Fibrosis Airways Disease

Cystic Fibrosis (CF) is a recessive genetic disease due to mutations of the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene encoding the CFTR chloride channel. The ion transport abnormalities related to CFTR mutation generate a dehydrated airway surface liquid (ASL) layer, which is responsible for an altered mucociliary clearance, favors infections and persistent inflammation that lead to progressive lung destruction and respiratory failure. The inflammatory response is normally followed by an active resolution phase to return to tissue homeostasis, which involves specialized pro-resolving mediators (SPMs). SPMs promote resolution of inflammation, clearance of microbes, tissue regeneration and reduce pain, but do not evoke unwanted immunosuppression. The airways of CF patients showed a decreased production of SPMs even in the absence of pathogens. SPMs levels in the airway correlated with CF patients' lung function. The prognosis for CF has greatly improved but there remains a critical need for more effective treatments that prevent excessive inflammation, lung damage, and declining pulmonary function for all CF patients. This review aims to highlight the recent understanding of CF airway inflammation and the possible impact of SPMs on functions that are altered in CF airways.

Triggering receptor expressed on myeloid cells-1 (TREM-1) as a therapeutic target in infectious and noninfectious disease: a critical review

The triggering receptor expressed on myeloid cells-1 (TREM-1) is an innate immune receptor found in the surface of several immune and non-immune cells. Since its first description in 2000, this molecule and its soluble form (sTREM-1) have been implicated in many diseases with infectious and noninfectious origins. As an amplifier of inflammation, the membrane-associated TREM-1 (mTREM-1) isoform induces the production of pro-inflammatory mediators, thus contributing to the pathogenesis of diseases such as sepsis, arthritis, colitis and infections. In this context, many studies have used molecules capable of inhibiting TREM-1 activity as anti-inflammatory drugs. In this regard, a few peptides have been showing promising results in the amelioration of detrimental immune responses. Some commercially available drugs, including corticosteroids and antibiotics, with known anti-inflammatory effects, have also shown activity in TREM-1 signaling. Therefore, considering the potential of this receptor as a therapeutic target, the present review encompasses the main compounds explored so far in TREM-1 modulation, highlighting and critically discussing its effects and major drawbacks of such approaches.

The development of diffuse panbronchiolitis during the treatment with long-term, low-dose clarithromycin for chronic sinusitis

Diffuse panbronchiolitis (DPB) is a progressive inflammatory airway disease characterized by a chronic cough, copious sputum expectation, dyspnea, and chronic sinusitis. Owing to the long-term treatment of low-dose macrolides, the prognosis has been remarkably improved. However, in some cases, patients are refractory to macrolides, and the subsequent treatment strategies are controversial. We herein present a patient with the onset of DPB during treatment with long-term, low-dose clarithromycin (CAM) for chronic sinusitis who was successfully treated by switching to long-term treatment with normal-dose CAM. We should recognize that DPB may develop in patients with chronic sinusitis despite treatment with a long-term, low-dose macrolide. We also propose that increasing the dose of macrolide may be a useful strategy for treating refractory patients.

Growth promotion in pigs by oxytetracycline coincides with down regulation of serum inflammatory parameters and of hibernation-associated protein HP-27

The growth promoting effect of supplementing animal feed with antibiotics like tetracycline has traditionally been attributed to their antibiotic character. However, more evidence has been accumulated on their direct anti-inflammatory effect during the last two decades. Here we used a pig model to explore the systemic molecular effect of feed supplementation with sub therapeutic levels of oxytetracycline (OTC) by analysis of serum proteome changes. Results showed that OTC promoted growth, coinciding with a significant down regulation of different serum proteins related to inflammation, oxidation and lipid metabolism, confirming the anti-inflammatory mechanism of OTC. Interestingly, apart from the classic acute phase reactants also down regulation was seen of a hibernation associated plasma protein (HP-27), which is to our knowledge the first description in pigs. Although the exact function in non-hibernators is unclear, down regulation of HP-27 could be consistent with increased appetite, which is possibly linked to the anti-inflammatory action of OTC. Given that pigs are good models for human medicine due to their genetic and physiologic resemblance, the present results might also be used for rational intervention in human diseases in which inflammation plays an important role such as obesity, type 2 diabetes and cardiovascular diseases.

Study of pharmacokinetic interaction of paroxetine and roxithromycin on bencycloquidium bromide in healthy subjects

PURPOSE

The aim of this study was to investigate the potential drug-drug interaction between Bencycloquidium bromide (BCQB) and paroxetine, and between BCQB and roxithromycin.

METHODS

Two studies were conducted on healthy male Chinese volunteers. Study A was an open-label, two-period, one-sequence crossover study (n=21). Each participant received a single nasal spray dose of BCQB 180μg on day 1. After a 7-day wash-out period, subjects received 20mg of paroxetine from day 8 to 17, and were co-administered 20mg of paroxetine and BCQB 180μg on day 18. In study B, participants (n=12) were randomly assigned to two groups. In period I, group A received BCQB 180μg on day 1, followed by the same dose four times daily from day 4 to 10, then, on day 11 a single dose of 150mg roxithromycin with BCQB 180μg were co-administered. In parallel, group B received a single dose of roxithromycin 150mg on day 1, followed by 300mg of roxithromycin from day 4 to 10, then, on day 11 a single dose of BCQB 180μg with roxithromycin 300mg were co-administered. After a wash-out time of 7days the respective treatments of each group (A and B) were swapped in period II. Blood samples were collected for pharmacokinetic analysis. Statistical comparison of pharmacokinetic parameters was performed to identify a possible drug interaction between treatments. Tolerability was evaluated by recording adverse events.

RESULTS

Study A: Geometric mean AUC0-36 for BCQB alone and co-administered with paroxetine were 474.3 and 631.3pgh/ml, respectively. The geometric mean ratio (GMR) of AUC0-36 was 1.33 (1.13-1.46), 90% C.Is, and was out the predefined bioequivalence interval (90% C.Is, 0.80-1.25). Geometric mean Cmax were 187.0 and 181.2pg/ml. Study B: The GMR of AUC0-36 was 0.98 (0.90-1.07), 90% C.Is for BCQB, and the GMR of AUC0-72 was 0.98 (0.87-1.11), 90% C.Is for roxithromycin. Both GMRs were within the predefined bioequivalence interval (90% C.Is, 0.80-1.25). Other pharmacokinetic parameters were within the predefined interval. No serious adverse events were reported and no significant clinical changes were observed in laboratory test results, vital signs and ECGs in any of the studies. All treatments were well tolerated.

CONCLUSION

The co-administration of BCQB with paroxetine showed a moderate increase in BCQB exposure, but was not clinically relevant. Also, no drug interaction was found between BCQB and roxithromycin.

New insights into the prevention of staphylococcal infections and toxic shock syndrome

Staphylococcus aureus is a major human pathogen capable of causing various diseases, from skin infections to life-threatening pneumonia and toxic shock syndrome. S. aureus exoproteins, including superantigens, contribute significantly to the pathogenesis of this organism. Antibiotics inhibit growth, but often provide no protection from S. aureus exoproteins. With the emergence of antibiotic-resistant S. aureus, new therapeutic options to treat or prevent S. aureus-associated diseases are critical. Most S. aureus infections begin on the skin or mucosal surfaces from direct inflammatory or cytotoxic effects of exotoxins. Therefore, antitoxin therapies that prevent toxin production and prevent their effects on host cells are being researched. Current treatments for staphylococcal diseases and recent developments in antitoxin therapeutic agents and vaccines are reviewed.

The effects of azithromycin on patients with diffuse panbronchiolitis: a retrospective study of 29 cases

BACKGROUND

Diffuse panbronchiolitis (DPB), a chronic inflammatory disease of the airway, is treated with macrolide antibiotics. The ability of azithromycin to improve DPB prognosis, as detected by high-resolution computed tomography (HRCT) scans and lung function tests, has not been studied in a large retrospective of patients. Our study aims to investigate the effects of azithromycin on patients with DPB using lung function tests and radiologic images.

METHODS

Twenty-nine patients with DPB were studied; their medical records were collected and analyzed retrospectively. Patients studied were hospitalized in the respiratory department of the Yixing Hospital, affiliated with Jiangsu University. Azithromycin was administered for 6-17 months. Changes in lung function and HRCT scans after treatment with azithromycin for six months were compared with pre-treatment values and images respectively.

RESULTS

Azithromycin therapy for six months resulted in rapid improvements in lung function, demonstrated by forced expiratory volume in one second (FEV1.0%), forced expiratory volume in one second over the forced vital capacity (FEV1.0/FVC), and forced expiratory volume with 75% vital capacity (FEF75%) values. In addition, improvements were seen in small nodular shadows, dilated peripheral bronchi, bronchial wall thickening, and tree-in-bud pattern, as detected by chest HRCT scans.

CONCLUSIONS

Long-term therapy with azithromycin is effective for patients with DPB.

Passive lung-targeted drug delivery systems via intravenous administration

The treatment of lung diseases including lung cancer and tuberculosis is one of the most challenging problems in clinical practice, because the conventional drug delivery systems cannot deliver drug effectively to the lung, which result in low therapeutic effect. Therefore, lung-targeted drug delivery systems (LTDDS) that can deliver drug to the lung in an effective way to increase drug concentration in lung tissue and reduce drug distribution in other organs and tissues become an ideal strategy to treat lung diseases. The LTDDS mainly include microparticles (microspheres and microencapsules), liposomes and nanoparticles via intravenous administration, and dry powder carriers and nebulized suspensions via pulmonary inhalation. As lungs possess the large absorptive surface area, the low thickness of the epithelial barrier and good blood supply, pulmonary inhalation has received great attention. Intravenous route is the commonly practiced method for administration of larger doses of drugs into the body. Numerous drugs can be delivered directly into general circulation by avoiding their first-pass metabolism and have potential to transport drugs to the lung via intravenous administration. This present article reviews the development, evaluation and application of LTDDS via intravenous administration for the treatment of lung diseases reported in the past decades.

Diffuse Panbronchiolitis

Diffuse panbronchiolitis (DPB) is characterized by chronic sinobronchial infection and diffuse bilateral micronodular pulmonary lesions consisting of inflammatory cells. Studies on disease etiology point to a genetic predisposition unique to Asians. Early therapy for DPB was largely symptomatic. The advent of macrolide antibiotics, including erythromycin, roxithromycin and clarithromycin, has strikingly changed disease prognosis. Low-dose, long-term macrolide therapy for DPB originated from detailed observations of response to therapy in a single patient. The bactericidal activity of macrolides, particularly erythromycin, is not a significant factor for their clinical efficacy in DPB. Firstly, irrespective of bacterial clearance, clinical improvement is observed in patients treated with erythromycin. Secondly, even in cases with bacterial superinfection with Pseudomonas aeruginosa resistant to macrolides, treatment has proved effective. Thirdly, the recommended dosage of macrolides produces peak levels in tissue that are below the minimum inhibitory concentrations for major pathogenic bacteria that colonize the airway. In the last two decades, the possible mechanism underlying the effectiveness of macrolide therapy has been extensively studied. The proposed mechanism of action includes inhibition of excessive mucus and water secretion from the airway epithelium, inhibition of neutrophil accumulation in the large airway, inhibition of lymphocyte and macrophage accumulation around the small airway, and modulation of bacterial virulence. The great success of macrolide therapy in diffuse panbronchiolitis may extend its application to the treatment of other chronic inflammatory disorders. If the anti-inflammatory activity of macrolides is independent of their bactericidal effect, new anti-inflammatory macrolides without antimicrobial activity should be developed to minimize emergence of macrolide-resistant micro-organisms.

Preparation and characteristics of erythromycin microspheres for lung targeting

BACKGROUND

If erythromycin is micronized into microspheres with suitable particle size, it can improve pulmonary drug concentration to maximize its effectiveness and minimize the adverse side effects.

AIM

In this study, erythromycin gelatin microspheres (EM-GMS) were prepared and some characteristics of EM-GMS were investigated. The drug-targeting index (DTI) of EM-GMS was evaluated to predict their potential as a targeted delivery system.

METHOD

Erythromycin was microencapsulated with gelatin by a double emulsion solvent evaporation method. Some characteristics of EM-GMS, including morphology, particle size, in vitro release, and safety were researched.

RESULTS

EM-GMS had a spherical shape and smooth surface morphology. The drug loading and encapsulation efficiency of EM-GMS were 13.56 +/- 0.25% and 55.82 +/- 2.23%, respectively. The release of erythromycin from EM-GMS showed an initial burst and following a sustained release, with an accumulate release of 80% at 4 hours. The EM-GMS was safe since there was no vein irritation and no hemolysis on the erythrocyte of rabbit at 3.5 mg/mL and a LD50 of 173.07 mg/kg. After administering EM-GMS to rabbits, the concentration of erythromycin in lung was 15.92 times higher than that in plasma and the DTI of EM-GMS in lung was 6.65 as compared with erythromycin lactobionate.

CONCLUSIONS

The preparation technology of EM-GMS for lung targeting was successful and the quality of microspheres was good.

Azithromycin effectiveness against intracellular infections of Francisella

Background

Macrolide antibiotics are commonly administered for bacterial respiratory illnesses. Azithromycin (Az) is especially noted for extremely high intracellular concentrations achieved within macrophages which is far greater than the serum concentration. Clinical strains of Type B Francisella (F.) tularensis have been reported to be resistant to Az, however our laboratory Francisella strains were found to be sensitive. We hypothesized that different strains/species of Francisella (including Type A) may have different susceptibilities to Az, a widely used and well-tolerated antibiotic.

Results

In vitro susceptibility testing of Az confirmed that F. tularensis subsp. holarctica Live Vaccine Strain (LVS) (Type B) was not sensitive while F. philomiragia, F. novicida, and Type A F. tularensis (NIH B38 and Schu S4 strain) were susceptible. In J774A.1 mouse macrophage cells infected with F. philomiragia, F. novicida, and F. tularensis LVS, 5 μg/ml Az applied extracellularly eliminated intracellular Francisella infections. A concentration of 25 μg/ml Az was required for Francisella-infected A549 human lung epithelial cells, suggesting that macrophages are more effective at concentrating Az than epithelial cells. Mutants of RND efflux components (tolC and ftlC) in F. novicida demonstrated less sensitivity to Az by MIC than the parental strain, but the tolC disc-inhibition assay demonstrated increased sensitivity, indicating a complex role for the outer-membrane transporter. Mutants of acrA and acrB mutants were less sensitive to Az than the parental strain, suggesting that AcrAB is not critical for the efflux of Az in F. novicida. In contrast, F. tularensis Schu S4 mutants ΔacrB and ΔacrA were more sensitive than the parental strain, indicating that the AcrAB may be important for Az efflux in F. tularensis Schu S4. F. novicida LPS O-antigen mutants (wbtN, wbtE, wbtQ and wbtA) were found to be less sensitive in vitro to Az compared to the wild-type. Az treatment prolonged the survival of Galleria (G.) mellonella infected with Francisella.

Conclusion

These studies demonstrate that Type A Francisella strains, as well as F. novicida and F. philomiragia, are sensitive to Az in vitro. Francisella LPS and the RND efflux pump may play a role in Az sensitivity. Az also has antimicrobial activity against intracellular Francisella, suggesting that the intracellular concentration of Az is high enough to be effective against multiple strains/species of Francisella, especially in macrophages. Az treatment prolonged survival an in vivo model of Francisella-infection.

Effects of tylosin on serum cytokine levels in healthy and lipopolysaccharide-treated mice

The effects of different doses of tylosin on serum cytokine concentrations were investigated in healthy and lipopolysaccharide-treated mice. The mice were divided into seven groups. Lipopolysaccharide (LPS) was injected into the positive control group. The other six groups received three different tylosin doses concurrently without or with LPS: 10 mg/kg, 100 mg/kg, 500 mg/kg, 10 mg/kg + LPS, 100 mg/kg + LPS and 500 mg/kg + LPS. After treatment, serum samples were collected at 0, 1, 2, 3, 6, 12 and 24 hours. Serum tumour necrosis factor alpha (TNFalpha), interleukin 1beta (IL1beta) and IL10 levels were determined by enzyme-linked immunosorbent assay (ELISA). Tylosin doses of 10 and 100 mg/kg induced no cytokine production in the healthy mice. Tylosin at 500 mg/kg had no effect on TNFalpha or IL1beta production, but it induced IL10 production in healthy mice. All doses of tylosin reduced the elevated TNFalpha and IL1beta in LPS-treated mice but increased their IL10 levels. In conclusion, these data suggest that tylosin has an immunomodulatory effect at the dose recommended for use against infection.

Antibiotics for the allergist: part 2

OBJECTIVE

To review antibiotic use and selection for disorders commonly seen in allergy practice.

DATA SOURCES

MEDLINE searches were performed cross-referencing antibiotic, antimicrobial, management, and treatment with multiple disorders commonly seen in allergy practice. References of the chosen articles were also examined.

STUDY SELECTION

Articles were selected based on their relevance to the subject matter.

RESULTS

A large body of research is available relevant to both conventional and novel uses of antibiotics. The use of antibiotics is in question for some disorders, whereas novel approaches to therapy with macrolide antibiotics are areas of active investigation. Meanwhile, patterns of microbial resistance continue to evolve.

CONCLUSION

For decades, antibiotics have been traditional first-line treatment for many disorders. Currently, this paradigm appears to be shifting as periods of observation come into favor and nonbacterial causes of inflammation are under greater scrutiny. Nonetheless, appropriate antibiotic selection often remains a key element in the treatment of these disorders. Knowledge of the relevant microbiology is an inherent requirement in selecting antibiotic therapies and necessitates awareness of current trends in bacterial resistance.

Oxygen uptake rate optimization with nitrogen regulation for erythromycin production and scale-up from 50 L to 372 m3 scale

Effects of different nitrogen sources on the erythromycin production were investigated in 50 l fermenter with multi-parameter monitoring system firstly. With the increase of soybean flour concentration from 27 g/l to 37 g/l to the culture medium, the erythromycin production had no obvious increase. Whereas adding corn steep liquor 15 g/l in the medium was beneficial for the production of erythromycin, the maximum erythromycin production was 22.2% higher than that of the control. It was found that corn steep liquor can regulate and enhance the oxygen uptake rate (OUR) which characterizes the activity of the microbial metabolism by inter-scale observation and data association. Both Intracellular and extracellular organic acids of central metabolism were analyzed, and it was found that the whole levels of lactic acid, pyruvic acid, citric acid, and propionic acid were higher than those of control before 64th h. The consumption amount of amino acids, which could be transformed into the precursors for erythromycin synthesis (i.e. threonine, serine, alanine, glycine and phenylalanine), were elevated compared with the control in erythromycin biosynthesis phase. The results indicated that corn steep liquor can regulate OUR to certain level in the early phase of fermentation, and enhance the metabolic flux of erythromycin biosynthesis. Erythromycin production was successfully scaled up from a laboratory scale (50 l fermenter) to an industrial scale (132 m(3) and 372 m(3)) using OUR as the scale-up parameter. Erythromycin production on industrial scale was similar to that at laboratory scale.

Where asthma and hypersensitivity pneumonitis meet and differ: noneosinophilic severe asthma

Asthma is a type-I allergic airway disease characterized by Th(2) cells and IgE. Episodes of bronchial inflammation, eosinophilic in nature and promoting bronchoconstriction, may become chronic and lead to persistent respiratory symptoms and irreversible structural airway changes. Representative mostly of mild to moderate asthma, this clinical definition fails to account for the atypical and often more severe phenotype found in a considerable proportion of asthmatics who have increased neutrophil cell counts in the airways as a distinguishing trait. Neutrophilic inflammation is a hallmark of another type of allergic airway pathology, hypersensitivity pneumonitis. Considered as an immune counterpart of asthma, hypersensitivity pneumonitis is a prototypical type-III allergic inflammatory reaction involving the alveoli and lung interstitium, steered by Th(1) cells and IgG and, in its chronic form, accompanied by fibrosis. Although pathologically very different and commonly approached as separate disorders, as discussed in this review, clinical studies as well as data from animal models reveal undeniable parallels between both airway diseases. Danger signaling elicited by the allergenic agent or by accompanying microbial patterns emerges as critical in enabling immune sensitization and in determining the type of sensitization and ensuing allergic disease. On this basis, we propose that asthma allergens cause severe noneosinophilic asthma because of sensitization in the presence of hypersensitivity pneumonitis-promoting danger signaling.

The Nonantibiotic Anti-Inflammatory Effect of Antimicrobial Growth Promoters, the Real Mode of Action? A Hypothesis

Societal concern and government regulations increasingly press for restricting the use of antibiotics as antimicrobial growth promoters (AGP). The search for alternatives is on, hampered by a lack of knowledge about the exact mechanism of AGP. Feed additives, such as AGP and alternatives, interact with the intestine. In the intestine, feed components, microbiota, and the mucosa interact in a very complex and dynamic way. Various mechanisms for AGP have been proposed, invariably based on the direct antibiotic influence on the microbial composition of the intestines. In the literature on antibiotics, however, the direct effects of antibiotics on host cells, in particular inflammatory cells, have been described. It is curious that this has never been considered in the literature on AGP. Presently, a case is being made that AGP most likely work as growth permitters by inhibiting the production and excretion of catabolic mediators by intestinal inflammatory cells. Concomitant or subsequent changes in microflora are most likely the consequence of an altered condition of the intestinal wall. This common, basic mechanism potentially offers an excellent explanation for the highly reproducible effects of AGP, as opposed to those obtained by alternatives aimed at microflora management. Therefore, the search for alternatives could be aimed at nonantibiotic compounds with an effect on the inflammatory system similar to that of AGP.

Infections and asthma

A new paradigm is developing in regard to the interaction between infection and asthma. This paradigm comprises the acute exacerbations seen in asthma and also asthma chronicity. Viral infections have been commonly evaluated in acute exacerbations, but findings suggest viral-allergen and viral-bacterial interactions are important for chronicity. Most recently, studies are also invoking atypical bacterial infections, Mycoplasma pneumoniae and Chlamydia pneumoniae, as factors in both acute exacerbation and chronic asthma.

Macrolides in cystic fibrosis

Macrolide antibiotics have been licensed since the 1950s and have an important role in the treatment of a diverse range of infectious diseases. Macrolide antibiotics have antibacterial activity against gram-positive bacteria, some gram-negative bacteria and intracellular pathogens. The spectrum of antibacterial activity combined with excellent intracellular and tissue penetration has led to the extensive use of this class of drugs in respiratory disease. Macrolide antibiotics also have demonstrated anti-inflammatory properties in various in vitro and in vivo model systems. Novel antimicrobial and anti-inflammatory properties of macrolide may result in clinical benefits, particularly in conditions where the infectious agent is inherently resistant to macrolides. Three randomized control trials have demonstrated improved lung function in patients treated with the macrolide antibiotic, azithromycin. Azithromycin was generally well tolerated and resulted in reduction in the inflammatory response which may be due to an immunomodulatory role. Short term studies (three to six months) have not demonstrated the development of increased bacterial resistance or the emergence of new pathogens following azithromycin.

Antibiotics in asthma

Asthma pathogenesis appears to be a result of a complex mixture of genetic and environmental influences. There is evidence that Mycoplasma pneumoniae and Chlamydia pneumoniae play a role in promoting airway inflammation that could contribute to the onset and clinical course of asthma. If antimicrobial therapy can eradicate these organisms, it might be possible to alter the course of the disease. Although antibiotics have no role in the routine management of acute exacerbations of asthma, certain macrolide antibiotics have been shown to have anti-inflammatory activity. Part of this effect is due to their known inhibition of steroid and theophylline metabolism, but through a myriad of mechanisms that are incompletely understood, macrolide antibiotics have additional broad anti-inflammatory properties that might prove useful in the management of asthma and other inflammatory diseases.

Macrolide and occult infection in asthma

PURPOSE OF REVIEW

A small percentage of asthma exacerbations are linked with infection by an atypical bacterium, such as Chlamydia pneumoniae or Mycoplasma pneumoniae. These bacteria also have been proposed to cause occult chronic lower airway inflammation and to initiate nonatopic asthma in adults. Consequently, the logical procedure would be to eliminate these pathogens as soon and as thoroughly as possible using antibiotics. Nonetheless, antibiotics are not recommended even for the treatment of acute asthma exacerbations except as needed for comorbid conditions. These discrepancies highlight the need to define the role, if any, of antimicrobials that are active against atypical pathogens, mainly macrolides, but also tetracyclines and fluoroquinolones, in the treatment of asthma.

RECENT FINDINGS

Macrolides are antibiotics with both antimicrobial and antiinflammatory activities. Some studies have documented that these agents could be useful in the treatment of occult infection in asthma because of their antimicrobial activity against atypical pathogens. They could also lead to reduction of the airways inflammation by decreasing the transcription of mRNA for a variety of cytokines and inhibiting interleukin-8 release by eosinophils, and therefore improvement of symptoms and pulmonary function. These effects are not caused by bronchodilation, elevation of serum theophylline level, or steroid-sparing mechanism.

SUMMARY

The available clinical evidence seems to support use of macrolides in the treatment of asthma because of their antimicrobial activity. However, studies that may confirm this hypothesis are scarce and with limited scientific value because of their open, uncontrolled design.

Addition of a macrolide to a beta-lactam-based empirical antibiotic regimen is associated with lower in-hospital mortality for patients with bacteremic pneumococcal pneumonia

To assess the association between inclusion of a macrolide in a beta-lactam-based empirical antibiotic regimen and mortality among patients with bacteremic pneumococcal pneumonia, 10 years of data from a database were analyzed. The total available set of putative prognostic factors was subjected to stepwise logistic regression, with in-hospital death as the dependent variable. Of the 409 patients analyzed, 238 (58%) received a beta-lactam plus a macrolide and 171 (42%) received a beta-lactam without a macrolide. Multivariate analysis revealed 4 variables to be independently associated with death: shock (P<.0001), age of >or=65 years (P=.02), infections with pathogens that have resistance to both penicillin and erythromycin (P=.04), and no inclusion of a macrolide in the initial antibiotic regimen (P=.03). For patients with bacteremic pneumococcal pneumonia, not adding a macrolide to a beta-lactam-based initial antibiotic regimen is an independent predictor of in-hospital mortality. However, only a randomized study can definitively determine whether this association is due to a real effect of macrolides.

Chorioamnionitis and brain injury

The limited available evidence supports a strong association of chorioamnionitis with neonatal encephalopathy and CP in the term infant. The association of chorioamnionitis with depressed Apgar scores or neonatal seizures and with CP is equivocal in the preterm infant. Different study results may be related to differences in study populations, perhaps specifically to differences in susceptibility by stages of neurologic development as well as differences in gene frequencies associated with inflammation and thrombophilia. We require further understanding of the normal roles of cytokines in brain development, pregnancy, and inflammatory homeostasis before clinical interventions directed at cytokines, their receptors, or the inflammatory process are considered.